No abstract

Pigeons were trained to peck at a transparent response key on which was projected either a color, brightness or pattern discrimination problem. Each subject was trained on only one of these problems. Training was continued until the subjects had reached asymptote. After reaching asymptote, subjects received brain ablations (by subpial suction) according to the following design: hyperstriate group, tissue removed from the Wulst; ablated controls, tissue removed from the neostriatum and corticoid areas; operated controls, no neural tissue intentionally removed. After a two week recovery period, each subject was re-tested on the same discrimination task that it had learned pre-operatively. Those birds with ablations of the Wulst showed deficits in performance on the brightness and pattern problems, but not on the color problem. Ablated and control subjects showed no post-operative deficits. These findings indicate that the Wulst functions in brightness and pattern discrimination, but may not be essential for color discrimination.

No abstract

Rats were reared in complex environments which differed in the density of animals per cage. After SO days they were tested on appetitive and aversivc learning tasks. Rats reared under crowded conditions showed generally poorer performance on complex tasks (appetitive maze learning, discriminated avoidance), while there were no significant differences on simpler tasks (inhibitory or one-way avoidance, appetitive straight alley running).

No abstract